Photoelectric motion transmitting device



' AHH/HUUUHWUUUUHUIWHHHH Apri14, 195o T. M. BERRY Y2,503,023

PHOTOELECTRIC MOTION TRANSMITTING DEVICE Filed Oct. 21, 1947 Fi g. 3.

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uvvuvvuuvvvvvvvvvv www Inventor: Theodo1^e MBeYTy,

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PHOTOELECTRIC MOTIOTRANSMITTING DEVICE Theodore M. Berry, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application october 21, 1947, serial No. 781,055

This invention relates to a motion transmitting device, and more particularly to such a device, the utilization of which does not require electrical or mechanical coupling to reproducel such motion. 'l n It is an object of the present invention to pro# vide a device of the type above described which does not require mechanical coupling, electrical coupling, or a combination of both, to reproduce the motion of ra 'component coupled thereto at a remote point.

Another object is to provide ajdevice which can reproduce the motion of acomponent coupled thereto at a remotev point without the introduction of substantially any friction between said device and the moving component coupled there- The above and other objects which are believed to be novel will be pointed out in the claims appended hereto.

In carrying out the present invention there is provided a Source light which may be-`modu` lated, for example, to pulsate in intensity at -a low frequency of the order of sixty cycles per second. Said modulated light is then directed through a polarizing arrangement coupled to the device, the motion. of which it is desired to reproduce. l The polarizing arrangement will sinusoidally alter the amount of transmitted light in accordance with the motion imparted to said polarizing means in other words, the polarizing arrangement attenuates the light by varying amounts responsive to the motion transmitted.

The light passing through thepolarizing means is directed toward a light sensitive arrangement, for example, a plurality of photoelectric cells in co-operative arrangement with said polarizing means. The light thus impinging on the photoelectric cells regulates the amount of electric current owing through the cells which, in turn, is suitably amplified. The amplied currents are conducted through a, suitable electric network to a receiver which is adapted to respond and reproduce the motion of the component actuatingy the polarizing means. Since there is neither electrical nor mechanical coupling between the component producing the motion and the device reproducing saidmotion, neither torque nor friction is developed and no energy will be given'u'p bythe motion-producing component to the reprodu'cing system. j y Although, by way of illustration, the means for altering the amountv of `light is described as a polarizing arrangement, any other suitable means' Claims. (Cl. Z50-232) capableof altering the intensity of the light sinusoidally in accordance with the motion of the component coupled to said means may be used. For

example, a member having a'rectangular apertureV through which the light passes may have disposed between it and the light an eccentrically pivoted, substantially circular member driven by said motion-producingcomponent. The amount of light passing through the aperture will depend on the position, at any instant, of the revolving eccentric member. As the eccentric member revolves, it cuts oir more or less light impinging on the ph'otoelectric cells in response to the motion imparted to itby the actuating means coupled thereto. Also, instead of modulating the light, such modulation may be introduced in the amplifying stages. Y

For a better understanding of the present .in-4 vention, reference is made in the following description tothe accompanying drawing in which Fig. 1 is a ypartially pictorial and partially diagrammatic representation of a preferred embodi-` ment of the'present invention; Figs. 2, 3 and 4 are waveforms Vwhich may be present, under certain circumstances, in different portions of the circuit illustrated :in Fig. 1, and Fig. 5 is an alternative arrangement for controlling the magnitude or intensity of a light source.

Referring now more particularly to Fig. 1, there isvshown a rotating member I0 adapted to be actuated by an electric motor II, or other suitable means. To reproduce the motion of said member I0 without substantially any friction or torque, there is provided, in this particular embodiment, a rotatable light polarizing disk I2, the

periphery of which isin contact with the plane surface of said motion producing member I0. Although thel disk I2 is shown as being driven directly by the member Ill for the sake of simplifying the description, other means may be resorted to for driving the disk I2 to impart thereto motion in accordance with the rotation of the member I0; It should be borne in mind that whatever means are utilized to drive the disk I2, the ldisk itself can be suitably supported or journalledso as to develop a minimum of friction.

In order kto transmit the motion of the member I0 to a point remote' from the location thereof, a

, Selsyn-like transmitting arrangement is providedv reflected light beams in the direction of the lightpolarizing disk I2. The light source is suitably asoaoza modulated, for example, at a frequency of the order of sixty cycles per second and is directed by the mirrors so as to pass through the disk I2 normal to its plane surface. On the opposite side of the rotatable light polarizing disk I2 are a plurality of fixed light polarizing disks Il, I8 and I9, the planes of polarization of which are permanently fixed at angles of 60 andk1i20 degrees to each other, respectively. The light beams coming through the fixed disks I1, I8 and I9 are directed toward a plurality of co-operating lightsensitive devices such as photoelectric cells'1 2U, 2 I. and 22. The light beams thus impinging on the photoelectric cells control the. amount of alter-v nating currents flowing there'through,V said cur-v rents being amplified by a plurality of co-operating ampliers 23, 24 and 25. While the preferred.

embodiment utilizes modulated light, the modulation component may be impressed across the input.

of the ampliers 23-25.

Regressing for the moment, itwill be noted that the output voltages of each of three, windings Qf a Selsyn transmitter or generator may be ei;-l pressed by the equations:

where pt is the angle of rotation of' the armature and w/21r is the input frequency, ci being a constant.

Referring again to Fig. 1,-if thev lighty source llil be modulated at a frequency ciw/211? and passed through the light polarizing disk I2 the stationary disk I9, the photocell 22 and the amplifier stage 25, the alternating current output of the ampli-y fier stage 25 may be represented by theA eguation: l

A E=a cos wt (1+cos2 pit) Where a is a constant and ptistheangle of rotation of the. polarizer disk I2; Bysubtracting,`

(a cos wt) fromv this equationone gets;

E=a cos wt cos 2-pt (4)- a cos wt cos 2 p-'t (5) a cos wt cos (2 p't-l-21r/3)l (6) a cos wt cos (2 p't-i-41r/3-) The outputs of the amplifiers 23-25 are con-,. nected to a Selsyn receiver or sofcalled Selsyn motor 26. The Selsyn motor or-.receiver 26 com. prises a stator 21 having three windings 28, 29.A and 30 and a rotor 3l having alsingle phase wind-` ing 32. The winding 32 is connected, in phase. with a primary winding 33 of a transformer 34, to an alternating current circuit 35. Theses? ondary of the transformer 34, comprises threewindings 36, 31 and 3.8 and these ar e conne cted, respectively, between the amplifiersV 23--25.and the stator windings 28-,3IL As thepolarizer disk` I2v turns, the Selsyn receiver 25 will turn inV response but at twice the angle that thepolarizer disk turns. This is due to the fact that the rotating disk l2 will produce in combination with.,

the other disks I--IS a maximum and minimum light intensity twice during the complete rotation of the disk I2 through 360 degrees.

Generally, in the operation of a motion transmitting system utilizing a Selsyn transmitter and receiver, the rotation of the rotor of the transmittel will induce in the stator windings thereof different values of voltage, depending on the relation of the magnetic axis of the rotor to the individual windings of the stator. These different values or" voltage are conducted to the stator windings of the receiver and will cause the magnetic axis of the rotor thereof to align itself with respect to the eld of its stator windings in accordance with said voltages. The rotor of the receiver thus transforms this stator field motion into mechanical motion which is in synchronism with the mechanical motion of the rotor of the transmitter and in phase relation with respect to the source of current energizing the windings of the two rotors.

In the embodiment of this invention, the Winding 33 functions with the rotor winding 32 to; maintain an in-phase relation between the re,-n ceiver 25 and the transmitter represented by the. transformer 34 and all of the componentsl connected thereto. The winding 33, being stationary,y cannot function as a rotor. However,` diierent., voltagevalues are transmitted tothe stator windv ingsI 28,- from the output of the amplifiers; 23-25 and the windings 36-38 and produce the, same effect as would therotor offaelsyn transmitter in the transmitting portion of the System.. These voltages (Equations 4,l 5, and V(5), having. different values in accordancey with theV rotation-y Of the light polarizing disk 12.., aspreviouslyfde-f scribed, will cause the magnetic axis of the rotor winding 32 to align itself in accordanceA withV the voltages present in the stator, windings` 28e-:30), although the angular motion of therotr: Zi'will,v be twice that of the rotating-disk; I2, as ,pieviously 639133.16111 Fig. 2 represents thewaveform of` thevoltageappearing at the input circuit 2,5( of the amplel- 25 when modulatedby the rotationy ofthepolaroicl disk I2. The frequency ofl thevaryingvoltage,

as represented by the-Wavem is theaIternationSi 'Y ofcurrent through the photoelectric cell 22.v as. produced by the frequency ofthe light I6'. InEig. 3 thelwaveform representsl thevoltage appearingy` across the secondary winding 381 and its frequency, although the same asv the frequency ofthel light I6, is degrees out of phase therewith. The al-gebraicsum ofthe waveforms of Figs. 2fand- 3 is shown` in Fig. 4. This last-mentioned voltage appears across one side 25 of-fthe amplifier 25 andone end 38' of the winding;

The above-described'` waveforms pertain to one portion of the transmitting circuit and" represents the result of the rotation of; the disk I 2jk through 180 degrees. It will be observedjthat the Waveform of Fig. 2 does notreversewheny it reaches the minimum magnitude or point 4I` butzcontinues inthe same phaseA sense llthe second portion 42. The application ofa voltageh of this waveform tothe Selsyn receivery 2 5 would. not operate receiver 26. However, theprpdncftion of a voltage having thewaveforrn, of- Eig4. isv suitable for Selsynoperation sinceitrever'ses, its phase every 180 degrees, as evidenced bythe points 43, 44 and45. It `will also be noted' vthat Within the range of 1 8() degrees of the vvayeform. 40, the modulation of the-waveform o f Fig. 4.J is twicethat of Fig.v2 as previously. explained,

InFig. 5. is' illustrated analternative method of controlling` the amount of light-incidenten the vphotoelectric cells 2li-22. This .arrangement comprises a plurality of mirrors 5U, 5| and-52 vsuitably supported atan angle with respect to the light {'6 so as` to reflect the light in the direction of the photoelectric cells 2li-22.. Disvposed between themirrors 50, 5l and 52 is an eccentrically pivoted disk 53. The disk 53 may be composed of any opaque material and is suitably fashioned to provide a sinusoidal variation of the reflectedv lightfrom the mirrors 50-52 .as itv intercepts the light directed-.toward the photoelectric lcells 2li- 22. A` plurality ofrlenses 54,

55 and 56 are disposed between the rotating disk'v .53^l and the photoelectric cells' 20.22.."in cooperative relation, with respect to the mirrors 513-52. These lenses serve to intercept the light reflected from the mirrors and direct same, as.- substantially parallel .beamS,-.toward the photoelectric cells. The disk 53 rmay be actuatedl by a second ldisk (not shown). Such a disk can be'attached to a shaft 5l which is affixed to the eccentric disk 53 and driven in the same manner as` disk i2. The operation of the above described arrangement for controlling the amount of light proceeds along the same lines as the polaroid disk control above described except thatone complete rotation of the eccentric disk 53 produces one revolution at the receiving or reproducing device 26. .l

The embodiments of the present invention which have been illustratedand described have been selected for the purpose of settinggforth the principles involved. It will be obvious that the-invention may be modified to meet various conditions in different specic uses and it is, therefore, intended to cover by the appended claims all such modifications which fall within the spirit and scope of the present invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A motion transmitting system having mo- J tion producing and reproducing means comprising, a source of light, means for intercepting said light to produce a plurality of light beams, means for sinusoidally varying said light beams in response to said motion producing means, a plurality of lightsensitive means responsive to said sinusoidally varying light beams, amplifying means coupled to said light-sensitive means for amplifying the current variations therethrough, an alternating current circuit, means for connecting the output of said alternating current circuit to the output of said amplifying means for producing a potential capable of reversing its phase periodically, and means for connecting said periodic phase-reversing potential to said motion reproducing means.

2. A motion transmitting system having motion producing and reproducing means comprising, a source of light, means for intercepting said light to produce a plurality of light beams, means for sinusoidally varying said light beams in response to said motion producing means, a plurality of light-sensitive means the current through which varies in response to said lsinusoidally varying light beams, amplifying means coupled to said light-sensitive means for amplifying the current variations therethrough, an alternating current circuit, means for connecting the output of said alternating current circuit to the output of said amplifying means for producing a potential capable of reversing its phase periodically, and means for connecting said :periodic phase-reversing potential to said motion reproducing means. .f

3. A motion transmitting system having motion producing-and reproducing `means comprising, a source of modulated light, means for intercepting said light to produce a' pluralityof light beams, rotatable light polarizing means coupled to said motion producing means and adapted to intercept said light beams for sinusoidally varying the amount thereof in response to said motion producing means, a plurality of light-sensitive means responsive lto said varying light beams, amplifying means coupled to said light-sensitive means for amplifying the variations thereof, an alternating current circuit,

means for connecting the output of said alternating current circuit to the output of said amplifying means for producing a potential capable Oreversing its phase periodically, and means for connecting said periodic phase-reversing potential to said motion reproducing means.

4. A motion transmitting system having motion producing and reproducing means comprising, a source of modulated light, rotatable light polarizing means coupled to said motion producing means, reflecting means adapted to reflect said light in the direction of said rotatable light polarizing means, relatively xed light polarizing means adapted to intercept the polarizedxlight passing through said rotatable light polarizing means for sinusoidally varying the amount of light passing through said fixed light polarizing means, al plurality of light-sensitive meansadapted to respond to said varying light, amplifying means coupled to said light-sensitive means for amplifying the variations thereof, an alternating current circuit, means for connecting the output of said alternating current circuit to the output of said amplifying means for producing a potential capable of reversing its -phase periodically, and means for connecting said periodic phasereversing potential to said motion reproducing means.

5. A motion transmitting system having motion producing and reproducing means comprising, a source of modulated light, means for converting said light to produce a plurality of light beams, an eccentrically pivoted shutter adapted to be actuated by said motion producing means and being disposed so as to intercept said light beams for sinusoidally varying same in response to said motion producing means, a plurality of light-sensitive means the current through which varies in response to said sinusoidally varying light beams, amplifying means coupled to said light-sensitive means for amplifying the current variations therethrough, an alternating current circuit, means for connecting the output of said alternating current circuit to the output of said amplifying means for producing a potential capable of reversing its phase periodically, and means for connecting said periodic phase-reversing potential to said motion reproducing means.

6. In a photoelectric motion transmitting device, the combination of means to provide at least three light beams pulsating in intensity at a predetermined frequency, means to attenuate these light beams by amounts having relative variations responsive to the motion transmitted, motion reproducing means operative in response to at least three electric currents of the same frequency as said light pulsations but degrees diierent in phase, and a plurality of photoelectric means to vary the amplitudes of said electric curof respective ones of suchflightibeams. y

In :La phot'o'electric mo'tion transmitting 5devic'e, the combination @offra light-polarizing disk,

means to 'rotate '.saidfdiskiresponsivetothe moj -responsive 'to 'variations in the attenuation foif A respective Kones ofsuchlightlbeams.

B. In a `photoelectri'c motion transmitting kdevice, the combination of an opaque disk/rotatable aboutaneccentric axis, `means torotatesaid disk responsive to :the motion l.transmitted, .means to direct three )light beams pulsating in intensity along respective Apatins 1,20 degreesapart around lthe laxis sof :said gdisk, so .that Lthe a disk intercepts andzattenuates the threebeamsfbyamounts hav.- ing relative variations Aas vthe disk .rotates :responsive to the motion transmitted, motion reproducing :means operative in response to three .electric :,currents 4of :thesame frequency =as=said lightpulsatons, but :1180 ,degreesdifeient in phase, and aplurality vOfpphotoelectric means to'vary the amplitudes lof said. electric currentsfresponsive to variations in the lattenuation (irrespective ones of suchlight beams.

"zifentsrzi'espoiislve fito-.variations iinfithe attenuation otionfuaiisiitterJeonipris meansimattenuare trfeseifghtrbeamszbyamounss h'avin rlativexvariatiorrs responsive. to itheinioL r'ansmitt'ed, la pluralityiof vphoteelectr-ic means Lto vary @the amplitudes of electric eure- -rents-,'sponsivetb variations fin the. attenua/tin df,-r'espectiveronesiofxsuch:currentsfendmeanslto ra ditto e'achsuchtcurrentaa cdns'tarit-:earriplitude 4cu.-Y eiit :ha-vingftlx'e fsameffreq-uency init 41130 'degreesifdiexfel emphase.

` ling-A zphotoelectrie motion aransniitterfeom- `p'lti'siri means v@to providea plurality "f of lfpulsatir .-ligritbeams,fgmeans1to:attenuatethese-:lightibean :lay` mounts :having irelative-variiations iesponsive to lthe motion transmitted, .a .pluralitylof .photo- -electric-zmeansIto'providefattenuatiiigelecticcui? -reritsrha ing-'a frequency uetermiredby the'liglht beam pul'satioixs Iandlhaving relative amplitudes iietermined bynzthe ,sre1ative flattenuation's f-bf the llightsbeams, and @means to add Tito each 'such #cuir-- y(rent ra .iconstantfamplitude nour-rent AIhavi-nlg the ysamefrequeneybiit 480 degreesfdifierent.inlphase.

25 yrr-HEeDoi-IE BERRY.

REEERENCES CITED y The following refer-ences 4are `of record vin lthe ,m 'leof thisvpatent:

UNITED STATES PATENTS Ni-mber Name lDate 15957236 Stewart A May '1, T1934 35 12,'11105368 'Lyle Dec.- l13,1938

12,-67'j484 Berry `July "25, V'1939 Certificate of Correction Patent No. 2,503,023 April 4, 1950 THEODORE M. BERRY It is hereby certified that error appears 1n he printed specification of the above numbered patent requiring correction as follows:

Column 3, line 26, for that I portion of the equation reading pt=21r/3 read pt-I-21r/8;

and that the said Letters Patent should be read With this correction therein that the same may conform to the record of the case in the Patent Oflce.

Signed and sealed this 26th day of September, A. D. 1950.

THOMAS F. MURPHY,

Assistant Uommz'sszoner of Patents. 

